The present invention relates to improvements in the method of making repairs to plaster and/or drywall board walls and ceilings.
In my copending application Ser. No. 722,840, issued as U.S. Pat. No. 4,632,790, Dec. 30, 1986 there is disclosed an inventive method for the repair of plaster, gypsum wallboard panels and the like used in the construction of walls and ceilings in private dwellings, office buildings and the like.
The disclosed method employs a high temperature-resistant, shrinkable film with a thickness from 20 to 100 mu which had been stretched during manufacture monoaxially and/or biaxially, at temperatures just below the solidification point of the polymer at a stretching ratio of between 1.1 to 3.0. This film is applied as a patch, over a crack and open joint in the plaster and wallboard and thereafter air heated while being so held. The film patch shrinks under the influence of temperatures above the stretching temperature, in proportions according to the stretching ratio. In the range of the shrink-producing temperatures the film becomes tacky and adhesive where it is in contact with the wall resulting in adhesion of the film to the contacted surface of the plaster and gypsum wall, while the film portion over the crack, and thus not in contact with any surface, shrinks and thus is devoid of any wrinkles.
Also, and most important, if inadvertently a force is applied against the repair patch area that is over the crack and creates a depression or wrinkles therein which extends into the void of the crack, it is a significant part of the present invention that external heat can again be applied to the patch and that responsive thereto the patch area covering the crack will again shrink and in this way again become devoid of the inadvertently caused depression or wrinkles.
In applying the repair patch it is necessary to initially tack the film patch to the wall surface, so that a close contact between the film and the wall surface exists prior to the application of heat. To effect this temporary attachment, strips of adhesive tape or masking tape is applied topically to the film and over its edges in contact with the film to the wall surface. It was also disclosed that one face of the film could be provided with a layer of an adhesive to be pressed against the wall surface. The result of the disclosed method is a completed covering providing a crack-free and virtual edgeless patch, that is a significant advance over the prior art methods for repair of surface cracks, edge and joints using spackling compound and the like.
It is the object of the present invention to provide an improvement over the aforementioned method in which the disadvantages enumerated above are overcome, and also to provide a repair patch that even after its initial application can be caused to have a smooth, non-detectable surface.
According to method aspects of the present invention, an improved method is provided for masking a crack in a drywall or plaster surface of a dwelling, comprising the steps of die cutting a repair patch from a heat shrinkable plastic film of a defined size presenting a surface area adapted to be placed in covering relation over the crack and bounded about its periphery by surrounding edges. The repair patch is manufactured with an adhesive confined to the surrounding edges only, and is placed over the crack to make an initial attachment to the drywall and heat is applied to the patch. The heat causes a contraction in size of the patch while exerting a pressure normal to the patch. This totally removes all wrinkles therefrom and the patch firmly attaches itself to the surface effectively masking from view the crack in the surface.
In a second embodiment, the heat shrinkable plastic is provided in strip form in a supply roll or the like. A selected length is adapted to be cut therefrom to serve as a repair patch. The plastic strip is provided with a previously applied adhesive confined to edges along opposite longitudinal sides of said plastic strip.